A supercritical carbon dioxide compressor low-leakage sealing system and control method

Abstract

The application relates to the technical field of supercritical carbon dioxide compressors, and discloses a low-leakage sealing system and a control method of a supercritical carbon dioxide compressor, which comprises a compressor body and a pressure-temperature control module. The compressor body is internally provided with a pressure-temperature control cavity in communication with the pressure-temperature control module and a leakage gas discharge cavity in communication with an atmospheric environment. A carbon ring seal is arranged between the pressure-temperature control cavity and the leakage gas discharge cavity. The front end of the pressure-temperature control cavity is provided with a comb seal. The comb seal, the pressure-temperature control cavity and the carbon ring seal form a multi-stage sealing combined structure. The application is suitable for a supercritical carbon dioxide compressor under a high-rotation-speed and high-pressure-difference working condition, and aims to solve the problems of bearing cooling difficulty, poor sealing effect and high complexity of a sealing control system in the prior art.

Description

Technical Field

[0001] This invention relates to the field of supercritical carbon dioxide compressor technology, and more specifically to a low-leakage sealing system and control method for a supercritical carbon dioxide compressor. Background Technology

[0002] Supercritical carbon dioxide, in its state above its critical point (31.1℃ and 7.38MPa), has the diffusivity of a gas and the high density of a liquid, making it suitable for high-efficiency thermal cycle systems. Supercritical carbon dioxide (SCO2) compressors are widely used in carbon dioxide power generation systems. They are characterized by high speed, high working fluid pressure, and large sealing pressure difference, which makes the shaft design and sealing problems of the compressor particularly complex.

[0003] In existing technologies, supercritical carbon dioxide compressors typically use oil-lubricated sliding bearings, and the seals usually employ dry gas seal technology or comb-tooth seal technology. Dry gas seals are a non-contact seal that isolates the sealing surface through a gas film; they are suitable for high-pressure conditions and offer good sealing performance but are relatively expensive. Comb-tooth seals are a multi-stage stepped sealing structure, suitable for initial pressure relief applications; they have a simple structure but relatively poor sealing performance.

[0004] Regarding bearing technology:

[0005] Oil-lubricated sliding bearings require a complex lubrication and cooling system to monitor and control oil pressure and temperature. Furthermore, these bearings have large clearances and high vibration levels. When used in conjunction with high-precision seals such as carbon ring seals, the high vibration can disrupt the seal's fit, thus reducing sealing effectiveness and service life.

[0006] While grease-lubricated angular contact ball bearings have small clearance, high precision, low vibration, and high load capacity, making them very suitable for the high-speed and high-pressure conditions of supercritical carbon dioxide compressors, their use in supercritical carbon dioxide compressors has not been widespread due to the significant increase in heat generation at high speeds and the inability to cool the bearings, which often leads to grease failure or even bearing damage.

[0007] Regarding sealing technology:

[0008] Comb seal: This sealing technology is simple and low-cost, but it has poor sealing effect at high speeds, resulting in a large amount of leakage.

[0009] Dry gas seals: While they can achieve lower leakage rates, they are expensive and require complex dry gas seal control systems, which increases the overall cost and maintenance difficulty of the equipment.

[0010] Carbon ring seals can achieve lower leakage, but due to their low pressure differential resistance, high shaft precision requirements, and susceptibility to damage under high pressure, they have not yet been widely used in supercritical carbon dioxide compressors.

[0011] Therefore, how to integrate the functions of bearings and seals, while ensuring stable operation of the compressor, reduces seal leakage and addresses the shortcomings of existing sealing solutions, is an urgent problem to be solved in the design of supercritical carbon dioxide compressors. Summary of the Invention

[0012] In view of this, the present invention provides a low-leakage sealing system and control method for a supercritical carbon dioxide compressor, which is applicable to supercritical carbon dioxide compressors under high speed and high pressure differential conditions, and aims to solve the problems of difficult bearing cooling, poor sealing effect and high complexity of sealing control system in the prior art.

[0013] To achieve the above objectives, the present invention provides a low-leakage sealing system for a supercritical carbon dioxide compressor, comprising a compressor body and a pressure-temperature control module. The compressor body is provided with a pressure-temperature control chamber connected to the pressure-temperature control module and a leakage gas discharge chamber connected to the atmospheric environment. A carbon ring seal is provided between the pressure-temperature control chamber and the leakage gas discharge chamber. A comb-tooth seal is provided at the front end of the pressure-temperature control chamber. The comb-tooth seal, the pressure-temperature control chamber, and the carbon ring seal constitute a multi-stage sealing combination structure.

[0014] The pressure-temperature control module is used to control the pressure and temperature of the working fluid inside the pressure-temperature control chamber.

[0015] Preferably, the compressor body includes a casing and a rotating shaft located at the central axis of the casing. The carbon ring seal is located inside the casing and sleeved on the bearing. The comb seal is located at the front end of the casing, and the front end of the comb seal is provided with a front cover plate.

[0016] Preferably, the comb seal is mounted on the front cover plate, the front cover plate is mounted on the housing, and the pressure and temperature control chamber is formed between the housing, the front cover plate, and the comb seal.

[0017] Preferably, the rear end of the casing is provided with a rear bearing housing, the rear end of the rear bearing housing is provided with an end cover, the end cover and the rear bearing housing form the leakage gas discharge chamber, and the end cover is provided with an exhaust hole that communicates with the leakage gas discharge chamber.

[0018] Preferably, the rotating shaft is provided with a front bearing and a rear bearing. The front bearing is located between the rotating shaft and the housing and is installed on the rotating shaft by a front locking nut. The rear bearing is located between the rotating shaft and the rear bearing housing and is installed on the rotating shaft by a rear locking nut. The vent hole is connected to the rear bearing.

[0019] Preferably, the front end of the front cover plate is provided with an impeller that is sleeved on the rotating shaft.

[0020] Preferably, the pressure-temperature control module includes a heater connected to the pressure-temperature control chamber, the outlet of the heater is connected to a CO2 storage tank, and a pressure control valve is provided on the pipeline connecting the heater and the CO2 storage tank.

[0021] Preferably, an exhaust valve is provided on the pipeline connecting the leak gas discharge chamber to the atmospheric environment.

[0022] Preferably, the system also includes a detection module, which includes a pressure sensor and a temperature sensor. The temperature sensor is installed on the casing and the rear bearing housing, respectively, to monitor the temperature of the front bearing and the rear bearing, as well as the temperature of the pressure-temperature control chamber. The pressure sensor is connected to the pressure-temperature control chamber via a pressure-sensing tube to monitor the pressure of the pressure-temperature control chamber.

[0023] A control method for a low-leakage sealing system of a supercritical carbon dioxide compressor as described above, comprising:

[0024] The high-pressure CO2 working fluid at the impeller outlet of the supercritical carbon dioxide compressor is depressurized by a comb-tooth seal and then enters the pressure-temperature control chamber. A pressure-temperature control module connected to the chamber controls the pressure and temperature, maintaining the working fluid pressure within the 2-4 MPa range. Within this range, the pressure and temperature of the working fluid are dynamically adjusted based on the monitored temperatures of the front and rear bearings to ensure the cooling effect adapts to changes in the thermal load of the bearings. The 2-4 MPa working fluid is sealed with a carbon ring seal, controlling leakage to within 0.5% of the main flow rate. After the sealed leaked gas cools the front and rear bearings, it enters the leaked gas discharge chamber through the exhaust port on the end cover and then exits into the atmosphere through the exhaust valve.

[0025] As can be seen from the above technical solution, compared with the prior art, the low-leakage sealing system for supercritical carbon dioxide compressors disclosed in this invention achieves stable support and sealing of supercritical carbon dioxide compressors under high pressure and high speed conditions, providing a low-cost and highly reliable solution for shaft support and sealing of supercritical carbon dioxide compressors, meeting the actual needs of the equipment under high pressure differential and high speed operating conditions, and has the following beneficial effects:

[0026] 1. Low cost, high efficiency, and low leakage: Through a multi-stage sealing combination of comb-tooth seal, pressure and temperature control chamber, and carbon ring seal, the leakage can be controlled to a low level of ≤0.5%, and the sealing system is simple and efficient.

[0027] 2. Improve shaft stability and bearing life: The bearing is cooled by the low-temperature sealing leakage gas, and the bearing temperature is dynamically regulated by monitoring the bearing temperature and using the pressure and temperature adjustable technology in the combined seal design. This allows grease-lubricated angular contact ball bearings to be used in high-speed supercritical carbon dioxide compressors, ensuring stable operation of grease-lubricated angular contact ball bearings under high-speed conditions. This eliminates the need for a complex lubrication oil supply system and improves the stability and life of the bearing.

[0028] 3. Improve sealing performance and stability: By combining high-precision angular contact ball bearings with carbon ring seals, the high precision and accurate positioning characteristics of the bearings are utilized to reduce the impact of shaft offset and vibration on the carbon ring seals, thereby further reducing leakage. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the overall structure of the low-leakage sealing system for the supercritical carbon dioxide compressor of the present invention;

[0031] Figure 2 This is a schematic diagram of the compressor body of the present invention.

[0032] Explanation of reference numerals in the attached diagram: 1. Compressor body; 2. Pressure and temperature control module; 3. CO2 storage tank; 4. Monitoring module; 5. Exhaust valve; 6. Atmospheric environment.

[0033] 1.1 Impeller; 1.2 Comb seal; 1.3 Pressure and temperature control chamber; 1.4 Casing; 1.5 Carbon ring seal; 1.6 Rear bearing housing; 1.7 Leakage gas discharge chamber; 1.8 Exhaust port; 1.9 Shaft; 1.10 End cover; 1.11 Rear lock nut; 1.12 Rear bearing; 1.13 Front bearing; 1.14 Front lock nut; 1.15 Front side cover plate. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of an exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Please see the appendix Figure 1-2 This invention discloses a low-leakage sealing system for a supercritical carbon dioxide compressor.

[0036] like Figure 1 As shown, the low-leakage sealing system for a supercritical carbon dioxide compressor provided by this invention includes a compressor body 1, a pressure and temperature control module 2, a CO2 storage tank 3, and a monitoring module 4. Figure 1-2 As shown, the compressor body 1 has a pressure and temperature control chamber 1.3 connected to the pressure and temperature control module 2 and a leakage gas discharge chamber 1.7 connected to the atmospheric environment 6. The working fluid in the pressure and temperature control chamber 1.3 is controlled by the pressure and temperature control module 2 to achieve pressure and temperature control of the working fluid in the pressure and temperature control chamber 1.3. After flowing through the pressure and temperature control module 2, the working fluid flows into the CO2 storage tank 3 through the pipeline. The leakage gas discharge chamber 1.7 collects the working fluid that is finally leaked in the sealing system and then safely discharges the leaked working fluid to ensure the safety of the system and environmental protection. The sealing leakage gas is discharged into the atmospheric environment 6 through the leakage gas discharge chamber 1.7 to avoid causing the CO2 concentration at the test site to be too high. The leakage gas discharge chamber 1.7 is in harmony with the atmospheric environment 6. An exhaust valve 1.5 is installed on the connected pipeline; the monitoring module 4 includes a pressure sensor and a temperature sensor. The temperature sensor is installed on the casing 1.4 and the rear bearing seat 1.6 respectively to monitor the temperature of the front bearing 1.13 and the rear bearing 1.12. The pressure sensor is connected to the pressure-temperature control chamber 1.3 through a pressure-sensing pipe to monitor the pressure of the pressure-temperature control chamber 1.3; a carbon ring seal 1.5 is provided between the pressure-temperature control chamber 1.3 and the leakage gas discharge chamber 1.7. A comb seal 1.2 is provided at the front end of the pressure-temperature control chamber 1.3. The comb seal 1.2, the pressure-temperature control chamber 1.3 and the carbon ring seal 1.5 form a multi-stage sealing combination structure, which can control the leakage within the range of ≤0.5%, achieving a simple and efficient effect.

[0037] The compressor body 1 is divided into rotating parts and stationary parts. The rotating parts include an impeller 1.1, a rotating shaft 1.9, a front locking nut 1.14, a rear locking nut 1.11, a front bearing 1.13, and a rear bearing 1.12. The stationary parts include a comb seal 1.2, a casing 1.4, a rear bearing seat 1.6, an end cover 1.9, and a side cover plate 1.15.

[0038] The rotating shaft 1.9 is located at the central shaft of the casing 1.4, and the comb seal 1.2 is located at the front end of the casing 1.4. The front end of the comb seal 1.2 is provided with a front cover plate 1.15. The comb seal 1.2 is installed on the front cover plate 1.15 by screws. The front cover plate 1.15 is installed on the casing 1.4 by screws. The casing 1.4, the front cover plate 1.15, and the comb seal 1.2 together form a pressure and temperature control chamber 1.3. The impeller 1.1 is installed at one end of the front end of the rotating shaft 1.9 by threads, which is also located at the front end of the front cover plate 1.15.

[0039] A carbon ring seal 1.5 is located inside the housing 1.4 and fitted onto the bearing 1.9. The carbon ring seal 1.5 is also mounted on the housing 1.4 with screws. The rear bearing housing 1.6 is located at the rear end of the housing 1.4 and is mounted on the housing 1.4 with screws and bolts. The end cover 1.10 is mounted on the rear bearing housing 1.6 and located at the rear end of the rear bearing housing 1.6. The end cover 1.10 and the rear bearing housing 1.6 form a leakage gas discharge chamber 1.7. The end cover 1.10 is provided with an exhaust hole 1.8 that communicates with the leakage gas discharge chamber 1.7.

[0040] The front bearing 1.13 and the rear bearing 1.12 are mounted on the rotating shaft 1.9, supporting the rotating component on the stationary component. Specifically, the front bearing 1.13 is located between the rotating shaft 1.9 and the housing 1.4 and is mounted on the rotating shaft 1.9 via the front locking nut 1.14, while the rear bearing 1.12 is located between the rotating shaft 1.9 and the rear bearing housing 1.6 and is mounted on the rotating shaft 1.9 via the rear locking nut 1.11. The vent 1.8 is connected to the rear bearing 1.12 so that after the sealing leakage gas cools the front bearing 1.13 and the rear bearing 1.12, it enters the leakage gas discharge chamber 1.7 from the rear bearing 1.12 through the vent 1.8 on the end cover 1.10.

[0041] Specifically, the front locking nut 1.14 and the rear locking nut 1.11 are threaded onto the rotating shaft 1.9 to fasten the front bearing 1.13 and the rear bearing 1.12 mounted on the rotating shaft 1.9 (both bearings are grease-lubricated angular contact ball bearings, which are bearing types that can simultaneously withstand combined radial and axial loads, and are particularly suitable for high-speed and high-load scenarios).

[0042] It should be noted that the comb seal 1.2 is located in the high-pressure area of ​​the leaking working fluid in the compressor impeller 1.1. The comb seal 1.2 reduces the working fluid pressure from 12-15 MPa to 2-4 MPa. The comb seal 1.2 reduces the pressure of the sealing gas through the principle of a multi-stage comb structure, thus reducing the burden on subsequent sealing stages.

[0043] The pressure-temperature control chamber 1.3 is located after the comb seal 1.2 and before the carbon ring seal 1.5. The pressure and temperature within the chamber are controlled by the pressure-temperature control module 2. The pressure-temperature control module 2 first ensures that the working fluid pressure in the pressure-temperature control chamber 1.3 is controlled within the range of 2-4 MPa to meet the operating conditions of the carbon ring seal and prevent damage to the carbon ring due to high pressure. Within this 2-4 MPa pressure range, the pressure of the working fluid in the pressure-temperature control chamber 1.3 is dynamically adjusted based on the bearing housing temperature, thereby controlling the working fluid temperature (the working fluid temperature varies with the working fluid pressure; at a working fluid pressure of 2-4 MPa, the working fluid temperature is between -20℃ and 5℃), ensuring that the cooling effect adapts to changes in the bearing's thermal load.

[0044] After being regulated by the pressure and temperature control chamber 1.3, the working fluid enters the carbon ring seal 1.5 device. The carbon ring seal 1.5 is a contact seal, which can significantly reduce the leakage of sealing gas and ensure the sealing effect of the compressor.

[0045] The low-pressure, low-leakage sealing gas after passing through the carbon ring seal 1.5 enters the leakage gas discharge chamber 1.7 and enters the atmospheric environment 6 through the leakage gas discharge pipe. A back pressure valve (i.e., exhaust valve 5) is installed on the discharge pipe to ensure that the leakage gas discharge chamber 1.7 is under a slight negative pressure (-0.05Mpa(G)), thereby ensuring that all CO2 sealing gas can be discharged through the leakage gas discharge pipe, thus avoiding excessively high CO2 concentration at the compressor test site.

[0046] Grease-lubricated angular contact ball bearings are used to support shaft systems. High-precision grease-lubricated angular contact ball bearings eliminate the need for complex lubrication systems and can reduce shaft misalignment and vibration, while optimizing the fit of the carbon ring seal. Temperature measuring points can be placed on the bearing housing to monitor the bearing temperature and dynamically adjust the temperature of the working fluid in the pressure and temperature control chamber.

[0047] The pressure and temperature control module 2 includes a water bath heater 2.1 connected to the pressure and temperature control chamber 1.3. The outlet of the water bath heater 2.1 is connected to a CO2 storage tank 3. A pressure control valve 2.2 is provided on the pipeline connecting the water bath heater 2.1 and the CO2 storage tank 3.

[0048] It should be noted that the water bath heater 2.1 is used to increase the temperature of the working fluid flowing through the pressure and temperature control valve (i.e., pressure control valve 2.2) before it enters the back pressure valve. Since the temperature of supercritical carbon dioxide decreases with decreasing pressure, when the working fluid is depressurized to 2-4 MPa via the comb seal 1.2, its temperature will correspondingly decrease by approximately -20℃ to 5℃. If the working fluid passes directly through the pressure and temperature control valve at this point, the temperature will continue to decrease, leading to the formation of dry ice (solid CO2), which will clog the valve. Therefore, the water bath heater is needed to raise the working fluid temperature to above 10℃ first, thereby preventing the formation of dry ice and ensuring the normal operation of the pressure and temperature control valve. After passing through the water bath heater, the working fluid passes through the pressure control valve 2.2, which controls the pressure and temperature of the pressure and temperature control chamber 1.3. The CO2 storage tank 3 collects the CO2 working fluid after passing through the pressure and temperature control module 2.

[0049] It should be noted that the water bath heater can be replaced with a steam heater, electric heater, or other heaters.

[0050] The control method for a low-leakage sealing system of a supercritical carbon dioxide compressor provided by the present invention includes:

[0051] The high-pressure CO2 working fluid from the outlet of the supercritical carbon dioxide compressor impeller 1.1 is depressurized by the comb-tooth seal 1.2 and then enters the pressure-temperature control chamber 1.3. The pressure and temperature in the chamber 1.3 are controlled by the pressure-temperature control module 2 connected to it, ensuring that the working fluid pressure is maintained within the range of 2-4 MPa to meet the operating conditions of the carbon ring seal 1.5 and prevent damage to the subsequent carbon ring seal 1.5 due to the high-pressure environment. Within this 2-4 MPa pressure range (the operating pressure of the pressure-temperature control chamber 1.3 can be adjusted according to the material of different carbon ring seals 1.5), the pressure is controlled within this range. The pressure and temperature of the working fluid in the pressure-temperature control chamber 1.3 are dynamically adjusted according to the monitored temperatures of the front bearing 1.13 and the rear bearing 1.12 to ensure that the cooling effect adapts to the heat load changes of the front bearing 1.13 and the rear bearing 1.12. The working fluid at 2-4 MPa is sealed by the carbon ring seal 1.5, which can control the leakage within 0.5% of the mainstream flow rate. After the sealed leakage gas cools the front bearing 1.13 and the rear bearing 1.12, it enters the leakage gas discharge chamber 1.7 through the exhaust port 1.8 on the end cover 1.10, and then enters the atmospheric environment 6 through the exhaust valve 5.

[0052] In this embodiment, the impeller outlet pressure of a supercritical carbon dioxide compressor is 12 MPa, the rotation speed is 40,000 r / min, and the bearing temperature rise is 60°C. This invention controls the pressure in the pressure-temperature control chamber 1.3 to 2-4 MPa (corresponding to a temperature of -19 to 5°C) through a pressure and temperature control valve to meet the usage requirements of the carbon ring seal 1.5. Then, the working fluid leakage rate is controlled to below 0.5% through the carbon ring seal 1.5. This invention controls the temperature of the leaking working fluid entering the bearing based on the measured temperature of the bearing (adjusted between -19 and 5°C), thereby using the leaking working fluid to achieve dynamic cooling of the bearing, keeping the bearing temperature below 45°C, and ensuring stable operation of the compressor.

[0053] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-leakage sealing system for a supercritical carbon dioxide compressor, characterized in that, The compressor body (1) includes a compressor body (1) and a pressure and temperature control module (2). The compressor body (1) is provided with a pressure and temperature control chamber (1.3) connected to the pressure and temperature control module (2) and a leakage gas discharge chamber (1.7) connected to the atmospheric environment (6). A carbon ring seal (1.5) is provided between the pressure and temperature control chamber (1.3) and the leakage gas discharge chamber (1.7). A comb seal (1.2) is provided at the front end of the pressure and temperature control chamber (1.3). The comb seal (1.2), the pressure and temperature control chamber (1.3) and the carbon ring seal (1.5) form a multi-stage sealing combination structure. The pressure-temperature control module (2) is used to control the pressure and temperature of the working fluid in the pressure-temperature control chamber (1.3); The compressor body (1) includes a casing (1.4) and a rotating shaft (1.9) located at the central axis of the casing (1.4). The carbon ring seal (1.5) is located inside the casing (1.4) and sleeved on the rotating shaft (1.9). The comb seal (1.2) is located at the front end of the casing (1.4), and the front end of the comb seal (1.2) is provided with a front cover plate (1.15). The comb seal (1.2) is installed on the front cover plate (1.15), the front cover plate (1.15) is installed on the housing (1.4), and the pressure and temperature control chamber (1.3) is formed between the housing (1.4), the front cover plate (1.15), and the comb seal (1.2). The rear end of the casing (1.4) is provided with a rear bearing seat (1.6), and the rear end of the rear bearing seat (1.6) is provided with an end cover (1.10). The leakage gas discharge chamber (1.7) is formed between the end cover (1.10) and the rear bearing seat (1.6). The end cover (1.10) is provided with an exhaust hole (1.8) that communicates with the leakage gas discharge chamber (1.7). The rotating shaft (1.9) is provided with a front bearing (1.13) and a rear bearing (1.12). The front bearing (1.13) is located between the rotating shaft (1.9) and the casing (1.4) and is installed on the rotating shaft (1.9) through a front locking nut (1.14). The rear bearing (1.12) is located between the rotating shaft (1.9) and the rear bearing seat (1.6) and is installed on the rotating shaft (1.9) through a rear locking nut (1.11). The exhaust hole (1.8) is connected to the rear bearing (1.12). The pressure and temperature control module (2) includes a heater connected to the pressure and temperature control chamber (1.3), the outlet of the heater is connected to a CO2 storage tank (3), and a pressure control valve (2.2) is provided on the pipeline connecting the heater and the CO2 storage tank (3). An exhaust valve (5) is provided on the pipeline connecting the leak gas discharge chamber (1.7) to the atmospheric environment (6).

2. The low-leakage sealing system for a supercritical carbon dioxide compressor according to claim 1, characterized in that, The front end of the front cover plate (1.15) is provided with an impeller (1.1) that is sleeved on the rotating shaft (1.9).

3. The low-leakage sealing system for a supercritical carbon dioxide compressor according to claim 1, characterized in that, It also includes a detection module (4), which includes a pressure sensor and a temperature sensor. The temperature sensor is installed on the casing (1.4) and the rear bearing seat (1.6) respectively to monitor the temperature of the front bearing (1.13) and the rear bearing (1.12). The pressure sensor is connected to the pressure-temperature control chamber (1.13) through a pressure-sensing tube to monitor the pressure of the pressure-temperature control chamber (1.3).

4. A control method for a low-leakage sealing system of a supercritical carbon dioxide compressor, applied to the low-leakage sealing system of a supercritical carbon dioxide compressor as described in any one of claims 1-3, characterized in that, include: The high-pressure CO2 working fluid at the outlet of the supercritical carbon dioxide compressor impeller (1.1) is depressurized by the comb seal (1.2) and enters the pressure-temperature control chamber (1.3). The pressure and temperature in the pressure-temperature control chamber (1.3) are controlled by the pressure-temperature control module (2) connected to the pressure-temperature control chamber (1.3), keeping the working fluid pressure in the pressure-temperature control chamber (1.3) within the range of 2-4 MPa. Within the pressure range of 2-4 MPa, the pressure is dynamically adjusted according to the monitored temperatures of the front bearing (1.13) and the rear bearing (1.12). The pressure and temperature of the working fluid in the temperature control chamber (1.3) are controlled to ensure that the cooling effect adapts to the heat load changes of the front bearing (1.13) and the rear bearing (1.12). The working fluid of 2-4 MPa is sealed by carbon ring seal (1.5) to control the leakage within 0.5% of the mainstream flow rate. After the sealed leakage gas cools the front bearing (1.13) and the rear bearing (1.12), it enters the leakage gas discharge chamber (1.7) through the exhaust hole (1.8) on the end cover (1.10) and then enters the atmospheric environment (6) through the exhaust valve (5).

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